It could be the opposite, fasteddie. Runners who would never have joined a club but who discover the pleasure of running and improving race times through Parkrun might then decide to join a club for proper tuition, training, guidance, further improvement and more variety over just weekly 5k runs. There are plenty of fee-paying club members who run Parkruns. (I'm one of them and, like you, happy to pay my fees even though I use few of the facilities.) There are plenty more runners who will join proper clubs thanks to the introduction to running that Parkruns gave them. On another point, if these runners go on to enter races and discover the benefits of affiliation in their entry fees, that would be another reason to join a club. Some will say that Parkruns take away from official clubs, but I see the opposite as being more likely, based on my experience of Parkruns over the past 3 - 4 years.